The Detection of Monoclinic Zirconia and Non-Uniform 3D Crystallographic Strain in a Re-Oxidized Ni-YSZ Solid Oxide Fuel Cell Anode
The solid oxide fuel cell (SOFC) anode is often composed of nickel (Ni) and yttria-stabilized zirconia (YSZ). The yttria is added in small quantities (e.g., 8 mol %) to maintain the crystallographic structure throughout the operating temperatures (e.g., room-temperature to >800 °C). The YSZ skele...
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MDPI AG
2020-10-01
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| Online Access: | https://www.mdpi.com/2073-4352/10/10/941 |
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| author | Thomas M. M. Heenan Antonis Vamvakeros Chun Tan Donal P. Finegan Sohrab R. Daemi Simon D. M. Jacques Andrew M. Beale Marco Di Michiel Dan J. L. Brett Paul R. Shearing |
| author_facet | Thomas M. M. Heenan Antonis Vamvakeros Chun Tan Donal P. Finegan Sohrab R. Daemi Simon D. M. Jacques Andrew M. Beale Marco Di Michiel Dan J. L. Brett Paul R. Shearing |
| author_sort | Thomas M. M. Heenan |
| collection | DOAJ |
| description | The solid oxide fuel cell (SOFC) anode is often composed of nickel (Ni) and yttria-stabilized zirconia (YSZ). The yttria is added in small quantities (e.g., 8 mol %) to maintain the crystallographic structure throughout the operating temperatures (e.g., room-temperature to >800 °C). The YSZ skeleton provides a constraining structural support that inhibits degradation mechanisms such as Ni agglomeration and thermal expansion miss-match between the anode and electrolyte layers. Within this structure, the Ni is deposited in the oxide form and then reduced during start-up; however, exposure to oxygen (e.g., during gasket failure) readily re-oxidizes the Ni back to NiO, impeding electrochemical performance and introducing complex structural stresses. In this work, we correlate lab-based X-ray computed tomography using zone plate focusing optics, with X-ray synchrotron diffraction computed tomography to explore the crystal structure of a partially re-oxidized Ni/NiO-YSZ electrode. These state-of-the-art techniques expose several novel findings: non-isotropic YSZ lattice distributions; the presence of monoclinic zirconia around the oxidation boundary; and metallic strain complications in the presence of variable yttria content. This work provides evidence that the reduction–oxidation processes may destabilize the YSZ structure, producing monoclinic zirconia and microscopic YSZ strain, which has implications upon the electrode’s mechanical integrity and thus lifetime of the SOFC. |
| first_indexed | 2024-03-10T15:34:15Z |
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| id | doaj.art-2050c8a85b3e4ba5a44d601e5465822d |
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| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-03-10T15:34:15Z |
| publishDate | 2020-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Crystals |
| spelling | doaj.art-2050c8a85b3e4ba5a44d601e5465822d2023-11-20T17:22:07ZengMDPI AGCrystals2073-43522020-10-01101094110.3390/cryst10100941The Detection of Monoclinic Zirconia and Non-Uniform 3D Crystallographic Strain in a Re-Oxidized Ni-YSZ Solid Oxide Fuel Cell AnodeThomas M. M. Heenan0Antonis Vamvakeros1Chun Tan2Donal P. Finegan3Sohrab R. Daemi4Simon D. M. Jacques5Andrew M. Beale6Marco Di Michiel7Dan J. L. Brett8Paul R. Shearing9The Electrochemical Innovation Lab, Department of Chemical Engineering, UCL, London WC1E 7JE, UKFinden Limited, Merchant House, 5 East St Helens Street, Abingdon OX14 5EG, UKThe Electrochemical Innovation Lab, Department of Chemical Engineering, UCL, London WC1E 7JE, UKNational Renewable Energy Laboratory, 15013 Denver W Parkway, Golden, CO 80401, USAThe Electrochemical Innovation Lab, Department of Chemical Engineering, UCL, London WC1E 7JE, UKFinden Limited, Merchant House, 5 East St Helens Street, Abingdon OX14 5EG, UKFinden Limited, Merchant House, 5 East St Helens Street, Abingdon OX14 5EG, UKESRF–The European Synchrotron, 71 Avenue des Martyrs, 38000 Grenoble, FranceThe Electrochemical Innovation Lab, Department of Chemical Engineering, UCL, London WC1E 7JE, UKThe Electrochemical Innovation Lab, Department of Chemical Engineering, UCL, London WC1E 7JE, UKThe solid oxide fuel cell (SOFC) anode is often composed of nickel (Ni) and yttria-stabilized zirconia (YSZ). The yttria is added in small quantities (e.g., 8 mol %) to maintain the crystallographic structure throughout the operating temperatures (e.g., room-temperature to >800 °C). The YSZ skeleton provides a constraining structural support that inhibits degradation mechanisms such as Ni agglomeration and thermal expansion miss-match between the anode and electrolyte layers. Within this structure, the Ni is deposited in the oxide form and then reduced during start-up; however, exposure to oxygen (e.g., during gasket failure) readily re-oxidizes the Ni back to NiO, impeding electrochemical performance and introducing complex structural stresses. In this work, we correlate lab-based X-ray computed tomography using zone plate focusing optics, with X-ray synchrotron diffraction computed tomography to explore the crystal structure of a partially re-oxidized Ni/NiO-YSZ electrode. These state-of-the-art techniques expose several novel findings: non-isotropic YSZ lattice distributions; the presence of monoclinic zirconia around the oxidation boundary; and metallic strain complications in the presence of variable yttria content. This work provides evidence that the reduction–oxidation processes may destabilize the YSZ structure, producing monoclinic zirconia and microscopic YSZ strain, which has implications upon the electrode’s mechanical integrity and thus lifetime of the SOFC.https://www.mdpi.com/2073-4352/10/10/941X-raydiffractioncomputed tomographySOFCfuel cellanode |
| spellingShingle | Thomas M. M. Heenan Antonis Vamvakeros Chun Tan Donal P. Finegan Sohrab R. Daemi Simon D. M. Jacques Andrew M. Beale Marco Di Michiel Dan J. L. Brett Paul R. Shearing The Detection of Monoclinic Zirconia and Non-Uniform 3D Crystallographic Strain in a Re-Oxidized Ni-YSZ Solid Oxide Fuel Cell Anode Crystals X-ray diffraction computed tomography SOFC fuel cell anode |
| title | The Detection of Monoclinic Zirconia and Non-Uniform 3D Crystallographic Strain in a Re-Oxidized Ni-YSZ Solid Oxide Fuel Cell Anode |
| title_full | The Detection of Monoclinic Zirconia and Non-Uniform 3D Crystallographic Strain in a Re-Oxidized Ni-YSZ Solid Oxide Fuel Cell Anode |
| title_fullStr | The Detection of Monoclinic Zirconia and Non-Uniform 3D Crystallographic Strain in a Re-Oxidized Ni-YSZ Solid Oxide Fuel Cell Anode |
| title_full_unstemmed | The Detection of Monoclinic Zirconia and Non-Uniform 3D Crystallographic Strain in a Re-Oxidized Ni-YSZ Solid Oxide Fuel Cell Anode |
| title_short | The Detection of Monoclinic Zirconia and Non-Uniform 3D Crystallographic Strain in a Re-Oxidized Ni-YSZ Solid Oxide Fuel Cell Anode |
| title_sort | detection of monoclinic zirconia and non uniform 3d crystallographic strain in a re oxidized ni ysz solid oxide fuel cell anode |
| topic | X-ray diffraction computed tomography SOFC fuel cell anode |
| url | https://www.mdpi.com/2073-4352/10/10/941 |
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